Allen-Bradley 1756-HYD02 User Manual page 232

Chapter 5 Configure Camming
232
discontinuities can exist between the end of the current profile and the start of the
new one. This process is done by using the Logix Designer Cam Profile Editor.
Once a pending position cam instruction has been executed, the new cam profile
takes effect automatically (and becomes the current profile). This process occurs
when the master axis passes through either the start or end point of the current
profile. If the current cam is configured to execute once, the new profile is initiated
at the completion of the current cam profile. The PC bit of the currently active
instruction (either MAPC or MATC) is also set.
If the current cam is configured to execute continuously, the new profile is
initiated at the completion of the current pass through the current cam profile.
The IP bit of the currently active instruction is also cleared. The motion controller
tracks the master axis position or time, depending on which instruction is used.
The slave axis position relative to the first profile at the time of the change and
uses this information to maintain synchronization between the profiles.
If the Execution Schedule of an instruction is set to Immediate and a position or
time cam profile is in process, the instruction errs. In this case, the instruction
generates an Illegal Dynamic Change error, error code 23, in the programming
software. This error even occurs when the axis is waiting to lock onto the master
axis. If an Execution Schedule of Pending is selected without a corresponding
position or time cam profile in progress, the instruction executes. However, no
camming motion occurs until another instruction with a non-pending Execution
Schedule is initiated. This process allows pending cam profiles to be preloaded
before executing the initial cam. This method addresses cases where immediate
cams would finish before the pending cam could be reliably loaded.
The Position or Time Cam Pending Status bit of the Motion Status word for the
specified slave axis is set to 1 (true). This process occurs after a Pending position
cam has been configured. When the pending (new) profile is initiated and
becomes the current profile, Position or Time Cam Pending Status bit is
immediately cleared as shown in this diagram.
Rockwell Automation Publication MOTION-UM002F-EN-P - February 2018